This invention relates generally to the field of millimeter-wave control devices, and more particularly, to a monolithic, millimeter-wave phase shifter.
Rectangular dielectric waveguide is used as the transmission medium in millimeter wave systems because it offers a low-loss characteristic and lends itself to low-cost fabrication. The lack of suitable control devices, such as phase shifters, for use in dielectric waveguide systems has, however, been as obstacle in creating fully integrated, monolithic designs. While there is relatively little previous art in the field of millimeter wave phase shifters, the designs which have been proposed use discrete elements such as diodes or ferrite toroids in various waveguide configurations. An example of this design format is found in U.S. Pat. No. 3,959,794 which implements conductivity modulation to alter the boundary conditions of a waveguide by using the distributive characteristics of a PIN diode appended to the guide.
The typical problems associated with many of these earlier devices arise from the use of the discrete elements which causes wave distortion and increases both the cost and complexity of the device.